In general, in a photolithography technique for manufacturing a semiconductor device, a semiconductor wafer or a flat panel display (FPD) substrate (hereinafter, referred to as a “wafer”) is coated with a photoresist, a resist film formed thereby is exposed along a predetermined circuit pattern, and the exposed pattern is developed to form a circuit pattern on the resist film.
In the photolithography process, a processing liquid such as, for example, a resist liquid or a developer supplied to the wafer may be mixed with bubbles such as nitrogen gas, or particles (foreign matters) by various causes. When the processing liquid mixed with bubbles or particles is supplied to a wafer, unevenness or defects may be caused in coating. Therefore, an apparatus for removing bubbles or particles mixed in the processing liquid is interposed in a conduit of the processing liquid.
Conventionally, as the kind of apparatuses, a processing liquid supplying apparatus is known in which a temporary storage container, a filter, and a pump are interposed in a supply pipe that connects a supply nozzle and a processing liquid storage container, and the processing liquid supplying apparatus includes a circulation pipe that connects the supply pipe and the filter between the processing liquid storage container and the temporary storage container, and a variable throttle that are provided in the circulation pipe (see, e.g., claims, and FIGS. 3 and 4 in Japanese Patent Laid-Open Publication No. 2010-135535). In order to facilitate the efficiency and diversification of processes performed in the photolithography process, the processing liquid supplying apparatus is provided with a plurality of supply nozzles, which are selectively used depending on an intended use.
In the processing liquid supplying apparatus, since gas dissolved in the processing liquid become bubbles when the liquid pressure of the processing liquid which is defoamed by the filter is reduced by the variable throttle, and the bubbles are removed by passing through the filter again via the supply pipe from the circulation pipe. Therefore, the gas dissolved in the processing liquid may be efficiently removed.